Vatican City, April 23 (Reuters): Pope Benedict today reminded journalists in four languages of their responsibility to seek the truth and defend human dignity and pledged to have a papacy as open to the media as his predecessor.

In a sign of how important communication will be to him as Pope, Benedict called the media that have converged in Rome from around the world to be the guests of his first audience for non-clergy since his election on Tuesday.

Benedict said he wanted to 'continue the fruitful dialogue' with the media begun by John Paul, who went down in history as a great communicator.

Benedict's message to the media was courteous but clear.

He stressed the 'ethical responsibility of those who work in the media, especially regarding the sincere search for truth and the defence of the centrality and dignity of the human person'.

Displaying his linguistic skills by speaking in Italian, English, French and his native German, he said each journalist had to contribute to the common good.

They should also understand the effect the media's recent breathless development can have 'on people's consciences and their spiritual outlook and in forming public opinion'.

Benedict, the former Cardinal Joseph Ratzinger, delivered his address confidently to some 4,000 journalists in the Vatican's huge audience hall.

He smiled often and was interrupted by applause, particularly when he began speaking his native German.

In order to do their work responsibly, the media's mandate was 'to discover the truth, to use it and to make it known,' said Benedict, wearing the traditional white papal cassock and looking professorial with gold-coloured wire-rimmed glasses.

Benedict celebrates his inaugural Mass in St Peter's Square tomorrow, delivering his first public homily as Pope from the spot where he presided over John Paul's funeral two weeks ago.

Fewer world leaders are due to attend the inauguration than the funeral, one of the biggest gatherings of the powerful in recent times, but royalty, presidents and prime ministers will attend, as will Pope's 81-year-old brother Georg.

Rome will shut off its airspace for the Mass and has anti-aircraft missiles and a Nato plane guarding against attack.

As the Pope spoke in the Vatican thousands of German pilgrims streamed towards Rome to attend the inauguration of their native son as leader of the world's 1.1 billion Catholics.

More than 1,000 volunteers have been drafted in to marshal the crowds, including some from a German-speaking area of northern Italy to help pilgrims from the Pope's homeland coming to see their first compatriot in centuries be sworn in as Pope.

Chancellor Gerhard Schroeder and President Horst Koehler are leading the German delegation. The US delegation is being led by Florida governor Jeb Bush, brother of George W. Bush.

In his address, Benedict also thanked the media for putting the Church in the spotlight in recent weeks, saying the blanket coverage had a unifying power for Catholics around the world.

The death of John Paul, his funeral and the conclave that elected Benedict was a media event like no other in recent history, with billions of viewers tuning in across the globe. Many said their faith was renewed from afar.

Saudi detention

Saudi Arabia has detained 40 Pakistani Christians for holding prayers at a house in the Muslim kingdom, where practising any religion other than Islam is illegal, newspapers said today. A group of men, women and children were attending the service in Riyadh when police raided the house, Al Jazirah newspaper said.